OCR Text |
Show 13 For simplicity for determining the applicable power range, ratings would at the manufacturers' standard ISO conditions. It is also stated that multiple small units cannot not be used to evade the intended emission targets. 3.8 PEAKING UNITS Peaking units are defined as those which normally operate less than 1500 hours per year. Requirements for flexibility created a modification to a 5-year, 7500 hour period, with a caveat that they could not run excessively during the potentially high-ozone summer months. Very small units are exempt from the emission targets, and all other new peaking turbines would have to control down to about 40-60 ppmv on natural gas, and 75-100 ppmv on distillate fuel (which is commonly used for peaking duty). The high start/acceleration reliability of peaking units will probably only be achieved with well-developed DLN combustors. Standby or emergency units which are not normally expected to operate are exempt from the Guideline. 3.9 EMISSION MONITORING New plants will be required to meaure their emissions of NOx and other contaminants to document their performance relative to emissions targets. The Guideline requires that any turbines larger than 25 MW producing electricity should have systems for continuous Emission Monitoring (CEM) , or methods of comparable effectiveness, as approved by the appropriate regulatory authority. These latter methods could be in the form of steam/water injection flow rate measurement (as required in the U.S.), or some type of predictive load analysis based on empirical data for the specific engine. other gas turbine installations would be required to have an annual emission test done to confirm performance. The detailed monitoring requirements are left for determination by the local regulatory authority. Some working group members believed that all units should be required to install CEM systems for continuous measurement throughout the year. However the majority of members felt that this was too onerous for the following reasons; -Gas turbi~es have a relatively narrow normal operating range, and performance is very predictable. Reliability and efficiency considerations preclude normal operations outside of this range. -The technology of CEM systems has not been fully demonstrated on all likely applications. Reliability, maintenance and the need for operating personnel may warrant against its effective use in remote operation and in isolated areas. |